Although the present invention is applicable to any electrically powered vehicle, it is especially useful on underground mining cars known as "scoop" cars. These cars scoop up and transport to a conveyor belt or to a larger capacity vehicle, such as a rail car or truck, fractured ore or coal that has been broken away from a fixed vein or deposit. Such cars are also used to transport equipment and supplies within an underground mine.
Conventional disc brakes when used on scoop cars, as may be seen in FIG. 6, are considered unreliable because they lack sufficient braking torque to stop or hold the car against a heavy load or against the power of the electric drive motor, which may be operated inadvertently by the operator. As often happens, operators forget to release the brake so that the car may be operated for some time with the brake engaged before burning up of the brake brings this problem to the operator's attention. Such occurrences result in rapid destruction of the brake and inoperable braking systems, which in turn cause federal mine safety violations.